THE BLOOD GROUPS OF MARINE ANIMALS
89
C . Antigen -antibody reactim.9
As already stated, there is a direct and relatively simple relation
between a gene and the antigen it conditions, a single gene direoting
the synthesis of antigenio molecules of a particular kind without much
if any interference from other genes or other factors in its environment.
The relation among these molecules and the antibodies with which
they are reactive is more complicated.
The concept involved may be arrived at by considering that, while
the structure of any kind of antigen is essentially invariant, antibody
molecules only combine with a small portion of this structure and vary
with respect to which portion this will be. A blood group gene o m
therefore be thought of as controlling an antigen, often termed an
agglutinogen, that presents a mosaic of patterns, each recognized by a
qualitatively different kind of antibody population. Each pattern
recognized is termed a blind factor, each gene therefore controlling an
agglutinogen identified by unique combinations of several such blood
factors. The individuality of a particular agglutinogen is demonstrated
by observing the integrity of its characteristic cluster of blood factors aa
this moves in association with its gene from one generation to the next.
The agglutinogens controlled by allelic genes, in addition to having
unique blood factors, can share some of the same or similar blood
factor patterns in different combinations, each total combinetion being
distinctive with respect to the particular allele that determinee it.
Cro8~-reactionrr can occur between reagent antiserums and heterologous
agglutinogens because of blood factors shared with the homologous
agglutinogen against which the reagents were prepared. These reactions
are found most frequently among the agglutinogens of allelic genes and
are apt to involve only a fraction of the total antibody population in
areagent because the blood factors concerned, while similar, may not
be identical. Shared blood factors not uncommonly result in &type
relationships among antigens that are controlled by genes occurring at
the same locus. Subtypes are demonstrated by absorption experiments
the nature of which is described in references cited at the sfart of this
article.
Antibody molecules can be divalent and have two separate a r e a
that are capable of combining with a blood factor. These are always
of the same specificity and are termed combining sites. The contact
between antibody and agglutinogen owes its speoiihity to the top@aPhy of the combining site areas of antibody which complement
and fit snugly in the manner of a template against the blood factor
Antibodies a n thus link two
together by combining with a blood faotor for which they BFB
with which they are reactive.
89
C . Antigen -antibody reactim.9
As already stated, there is a direct and relatively simple relation
between a gene and the antigen it conditions, a single gene direoting
the synthesis of antigenio molecules of a particular kind without much
if any interference from other genes or other factors in its environment.
The relation among these molecules and the antibodies with which
they are reactive is more complicated.
The concept involved may be arrived at by considering that, while
the structure of any kind of antigen is essentially invariant, antibody
molecules only combine with a small portion of this structure and vary
with respect to which portion this will be. A blood group gene o m
therefore be thought of as controlling an antigen, often termed an
agglutinogen, that presents a mosaic of patterns, each recognized by a
qualitatively different kind of antibody population. Each pattern
recognized is termed a blind factor, each gene therefore controlling an
agglutinogen identified by unique combinations of several such blood
factors. The individuality of a particular agglutinogen is demonstrated
by observing the integrity of its characteristic cluster of blood factors aa
this moves in association with its gene from one generation to the next.
The agglutinogens controlled by allelic genes, in addition to having
unique blood factors, can share some of the same or similar blood
factor patterns in different combinations, each total combinetion being
distinctive with respect to the particular allele that determinee it.
Cro8~-reactionrr can occur between reagent antiserums and heterologous
agglutinogens because of blood factors shared with the homologous
agglutinogen against which the reagents were prepared. These reactions
are found most frequently among the agglutinogens of allelic genes and
are apt to involve only a fraction of the total antibody population in
areagent because the blood factors concerned, while similar, may not
be identical. Shared blood factors not uncommonly result in &type
relationships among antigens that are controlled by genes occurring at
the same locus. Subtypes are demonstrated by absorption experiments
the nature of which is described in references cited at the sfart of this
article.
Antibody molecules can be divalent and have two separate a r e a
that are capable of combining with a blood factor. These are always
of the same specificity and are termed combining sites. The contact
between antibody and agglutinogen owes its speoiihity to the top@aPhy of the combining site areas of antibody which complement
and fit snugly in the manner of a template against the blood factor
Antibodies a n thus link two
together by combining with a blood faotor for which they BFB
with which they are reactive.